1. Field of the Invention
This invention relates to a method of N-phosphorylating acidic heterocyclic amines such as pyrrole and indole.
2. Description of the Prior Art
Greenly et al. in J. Org. Chem., 29 1009 (1964) described a method of phosphorylating pyrrole to produce N-(dimethylphosphonyl) pyrrole in which the potassium salt of pyrrole is reacted with O,O-dimethylphosphorochloridate.
U.S. Pat. No. 3,816,452 describes a method wherein the potassium salt of pyrrole is reacted with dialkyl phosphorochloridite to form an intermediate which is then treated with sulfur to yield a N-(dialkylthiophosphonyl) pyrrole or with an oxygen oxidant to yield N-(dialkyloxyphosphonyl) pyrrole. The products produced from these reactions are disclosed as being useful as flame retardants.